Polishing composition



Patented Apr. 12, 1927..

- em rge STATES A D BRYANT rrsnna or new Yomc, Ni Y. H

POLISHING ooMPosI'rIoN.

No'iiraivin' i made and readily presented on the market in various forms, either as a dust or granular mass in boxes or compressed in the form of sticks or cakes.

A further object concerns the provision of a composition which is especially useful to photo-engravers for the purpose of polishing and graining zinc and copper plates.

iVhen the photo-engravers receive zinc and copper plates from the manufacturers these plates are cut up into smaller plates and in most cases ordinary powdered pumice is rubbed over the surface with a pad of felt, absorbent cotton, or even cloth under running water. This rubbing continues until the surface of the plate is finely grained. Other engravers may use charcoal,

which removessurface grease, and also gives a fine tooth or grain to the metal. The whole idea of polishing the plates with pumice is to give them a, fine tooth so. that the chemicals with which they are treated more readily cling to the surface of the. metal. Charcoal is principally used by the engravers on copper plates, because high class half-tones are generally done on copper and a slight scratch on the surface would show through the enamel when printed.

Charcoal is also used on copper because the copper is very hard and charcoal cuts it better than pumice. My compound is intended to replacethe charcoal for use in treating I copper plates as well as zinc plates.

' My principal idea in developing the com position on which I desire to obtain a patent is to have it replace pumice as ordinarily used, as it, will do the work better, and qu er- My composition in general comprises very finely divided or ground metal dust, Very tity of oil.

"A lication filed Aprn 14, 1924. Serial No. 706,560.

finely groundedpumice, and. a small quan- Sometimes I find it desirable to provide the composition with small quanti ties of fine particles of felt or fibrous mate rial. The metal dust provided in the compo sition may be zinc, copper or any other-desirable metal. Preferablv the metal dust for any particular polishing composition is the dust of the metal the plates of which the composition is intended to polish or grind.

For instance, if we sell the composition for polishing copper plates, then the metal dust in this form of the composition will be a fine copper dust;,whereas if we sell the composition foi" the purpose of grinding or polishing zinc plates, then the metal dust is finely divided zinc dust.

Preferably the percentage of metal dust in the composition will run between ten and twenty per cent, being-largely finely ground pumice and a small percentage of oil, and m;-some cases a small percentage of finely divided felt or fibrous material. The oil gives the mixture the proper greasiness and acts as a sort of binder to intimately incorporate the various ingredients together.

These ingredients may be subjected to pressure to form sticks'or blocks or cakes,

in which case a small quantity of lard orfat is added to act as an additional binder.

The most important feature of this composition, asidefrom the particular ingredients used, is the fineness to which the metal dust, the pum1ce and the fiber are ground.

- The particular composition will do the olishin or rinding work for the en aversmuchbetter and quicker than straight pumice because the use of powdered zinc against zinc plates and powdered copper against copper plates makes a wonderful engraving plants encounter in the purchase of pumice is that they cannot get very finely groundpumice, and the kind they usually obtain is very poorly graded and scratches their'plates. The variableness of the'qua-lity of the'pumice obtained causes conslderable trouble. By reason of the fact that this composition is ground to exceeding fineness and varies only to a small extent withincertain limits,'the character of the polishabrasive. The great difficulty that photo" I ing composition can be regulated so that a standard, uniform product is available for the buyers.

hat I'claim is:

1. A polishing composition, Which comprises an intimate mixture of finely divided metal dust, pumice and oil.

2. A polishing composition, which comprises and intimate mixture of ten to twenty per cent finely divided metal dust and pumice.

3. A polishing composition, which comprises an intimate mixture of very finely metal dust being ten to twenty per cent of the bulk while the oil is suflicient to cause the bulk to be a paste.

ALFRED BRYANT FISHER. 

